PROJECT SUMMARY Young Black gay, bisexual and other men who have sex with men (YB-GBMSM) are disproportionately impacted by HIV, with suboptimal rates of engagement across the HIV Continuum of Care (HIV-CoC). Mental health (MH) comorbidities contribute to poor HIV care engagement for many YB-GBMSM; however, effective treatment for these conditions is hindered by barriers including logistical challenges, medical mistrust, and MH stigma. The Ryan White Care act supports integration of HIV and MH services; however, our preliminary studies demonstrate low rates of MH referrals and MH care engagement among YB-GBMSM living with HIV, even in these ostensibly integrated care settings. To our knowledge, there are no published interventions designed specifically to improve MH care engagement among YB-GBMSM living with HIV. The objective of this R34 application is to develop and implement CHIMES (Cross-disciplinary HIV Integrated with Mental Health Support), a clinic- and provider-level intervention to improve HIV-MH care integration and MH care engagement among YB-GBMSM attending Ryan White clinics. The rationale for the project is that efforts to improve integration of services, particularly if they are culturally tailored, are likely to increase MH and HIV care engagement for YB-GBMSM. The proposed study will pursue two specific aims: (1) to develop the CHIMES intervention; and (2) to conduct a hybrid type 2 implementation-effectiveness pilot trial of CHIMES in two HRSA/Ryan White-funded clinics in Atlanta, Georgia ? a city in the heart of the Southern HIV epidemic. For the first aim, we will work collaboratively with provider and patient stakeholders, adapt existing evidence-based interventions, and build on formative data to refine intervention content, informed by the Capability- Opportunity-Motivation-Behavior (COM-B) Model. For the second aim, we will implement CHIMES in the two clinic settings and conduct a mixed-methods assessment in which continuous data collection informed by the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework will be used to evaluate effectiveness and implementation processes. Upon completion of these aims, we will have collected rich data to inform a subsequent, larger scale implementation trial of CHIMES. We introduce significant innovations including the characterization of an integrated HIV-MH care continuum and prioritization of cultural and developmental factors (both barriers and facilitators) specific to YB-GBMSM within established implementation science frameworks. The proposed research is significant because of its potential to inform effective strategies for improving HIV viral suppression and quality of life among YB-GBMSM, leading to improved individual and public health outcomes in line with the goals of the Ending the HIV Epidemic initiative.